[Winpcap-users] sleep in pcap_next_ex api

Prasanna Kumar Nelam prasannakumar.n at imimobile.com
Tue Jul 14 03:27:55 PDT 2009


Dear All,

 

I am using pcap_next_ex() API to read the packets from Network. In my
application I implemented 2 threads one for reading the packets from
network, and other for process these packets.

I am giving the code snippet, can u please suggest me whether it is correct
or not.

 

while(true)

{

while((res=pcap_next_ex(pcap.m_padhandle,&header,&pkt_data))>0)

            {

 
////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////

The lines below are used to copy the captured pkt into our local buffer

 

packet_capture *packet=new packet_capture();

 
packet->header=(pcap_pkthdr*)malloc(sizeof(pcap_pkthdr)+1);//header;

 
memset((void*)packet->header,0,(sizeof(pcap_pkthdr)+1));

                        memcpy(packet->header,header,sizeof(pcap_pkthdr));

                        packet->pkt_data=(unsigned
char*)malloc((int)header->caplen+1);                         

 
memset((void*)packet->pkt_data,0,(int)header->caplen+1);

 
memcpy((void*)packet->pkt_data,(void*)pkt_data,(int)header->caplen);

 
////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////
///////////

 
****************************************************************************
********************************************************

                        The following lines are used to put the packet into
queue, the packets from this C++queue are read by another thread 

 {

                                    CAutoLock lock(g_syncpkt);

                                    pkt_capture.push(packet);

                                    printf("\n the queue size
is:%d\n",pkt_capture.size());

                        }

 
****************************************************************************
***********************************************************

                        Sleep(1); 

            }

            if(res==-1)

            {

                        printf("Error reading the packets: %s\n",
pcap_geterr(pcap.m_padhandle));

                        FILE *fp;

                        fp=fopen("exceptionhandler.log","a");

                        fprintf(fp,"%s-%s\n","Error reading the packets",
pcap_geterr(pcap.m_padhandle));

                        fclose(fp);

 

            }

            Sleep(1);

            

}

 

My doubt is it correct to write Sleep() at the
while((res=pcap_next_ex(pcap.m_padhandle,&header,&pkt_data))>0) loop, by
putting the sleep shall we loss any packet.

 

Before intrducing the Sleep() in the code, I am getting delayed processing
thread, and I am not able to process the packets immediately after
capturing, because of that the virtual memory is increasing.

Thanks in Advance for your advice.

 

 

 

Thanks and Regds,

Prasanna Kumar.N,

Software Engineer,

R&D Networks,

Mob:9000086538

 

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